/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.tsfile.read.filter.operator;

import org.apache.iotdb.tsfile.file.metadata.statistics.Statistics;
import org.apache.iotdb.tsfile.read.filter.basic.Filter;
import org.apache.iotdb.tsfile.read.filter.factory.FilterSerializeId;
import org.apache.iotdb.tsfile.read.filter.factory.FilterType;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;

import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/**
 * Like.
 *
 * @param <T> comparable data type
 */
public class Like<T extends Comparable<T>> implements Filter {

    private static final long serialVersionUID = 2171102599229260789L;

    protected String value;

    protected FilterType filterType;

    protected Pattern pattern;

    private Like() {
    }

    /**
     * The main idea of this part comes from
     * https://codereview.stackexchange.com/questions/36861/convert-sql-like-to-regex/36864
     */
    public Like(String value, FilterType filterType) {
        this.value = value;
        this.filterType = filterType;
        try {
            String unescapeValue = unescapeString(value);
            String specialRegexStr = ".^$*+?{}[]|()";
            StringBuilder patternStrBuild = new StringBuilder();
            patternStrBuild.append("^");
            for (int i = 0; i < unescapeValue.length(); i++) {
                String ch = String.valueOf(unescapeValue.charAt(i));
                if (specialRegexStr.contains(ch)) {
                    ch = "\\" + unescapeValue.charAt(i);
                }
                if ((i == 0)
                        || (i > 0 && !"\\".equals(String.valueOf(unescapeValue.charAt(i - 1))))
                        || (i >= 2
                        && "\\\\"
                        .equals(
                                patternStrBuild.substring(
                                        patternStrBuild.length() - 2, patternStrBuild.length())))) {
                    String replaceStr = ch.replace("%", ".*?").replace("_", ".");
                    patternStrBuild.append(replaceStr);
                } else {
                    patternStrBuild.append(ch);
                }
            }
            patternStrBuild.append("$");
            this.pattern = Pattern.compile(patternStrBuild.toString());
        } catch (PatternSyntaxException e) {
            throw new PatternSyntaxException("Regular expression error", value.toString(), e.getIndex());
        }
    }

    @Override
    public boolean satisfy(Statistics statistics) {
        return true;
    }

    @Override
    public boolean satisfy(long time, Object value) {
        if (filterType != FilterType.VALUE_FILTER) {
            return false;
        }
        return pattern.matcher(value.toString()).find();
    }

    @Override
    public boolean satisfyStartEndTime(long startTime, long endTime) {
        return true;
    }

    @Override
    public boolean containStartEndTime(long startTime, long endTime) {
        return true;
    }

    @Override
    public Filter copy() {
        return new Like(value, filterType);
    }

    @Override
    public void serialize(DataOutputStream outputStream) {
        try {
            outputStream.write(getSerializeId().ordinal());
            outputStream.write(filterType.ordinal());
            ReadWriteIOUtils.writeObject(value, outputStream);
        } catch (IOException ex) {
            throw new IllegalArgumentException("Failed to serialize outputStream of type:", ex);
        }
    }

    @Override
    public void deserialize(ByteBuffer buffer) {
        filterType = FilterType.values()[buffer.get()];
        value = ReadWriteIOUtils.readString(buffer);
    }

    @Override
    public String toString() {
        return filterType + " is " + value;
    }

    @Override
    public FilterSerializeId getSerializeId() {
        return FilterSerializeId.LIKE;
    }

    /**
     * This Method is for unescaping strings except '\' before special string '%', '_', '\', because
     * we need to use '\' to judege whether to replace this to regexp string
     */
    public String unescapeString(String value) {
        String out = "";
        for (int i = 0; i < value.length(); i++) {
            String ch = String.valueOf(value.charAt(i));
            if ("\\".equals(ch)) {
                if (i < value.length() - 1) {
                    String nextChar = String.valueOf(value.charAt(i + 1));
                    if ("%".equals(nextChar) || "_".equals(nextChar) || "\\".equals(nextChar)) {
                        out = out + ch;
                    }
                    if ("\\".equals(nextChar)) {
                        i++;
                    }
                }
            } else {
                out = out + ch;
            }
        }
        return out;
    }
}
